Downdraft electrical furnace.



N0. 64l,976. Patented Jan. 23, I900. R. H. LAIRD. A

DDWNDRAFT ELECTRICAL FURNACE. I (A splication filed Jul 24, 1897.) (No Mddel.) 2 Sheets Sheet I.

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No. 641,976. Patented Ian. 23, I900. R. H. LAIRD.

DOWNDRAFT ELECTRICAL FURNACE.

(Application filed July 24, 1897.)

2 Sheets-Sheet 2.

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THE NORRIS PETERS 00., PuoTuumQ, WASHINGTON a. c

UNITED STATES PATENT OFFICE.

ROBERT H. LAIRD, OF PITTSBURG, PENNSYLVANIA.

DOWNDRAFT ELECTRICAL FURNACE.

SPECIFICATION forming part of Letters Patent No. 641,976, dated anuary 23, 1900.

Application filed July 24,1897.

T0 ctZZ whont it may concern:

Be it known that I, ROBERT H. LAIRD, a

citizen of the United States of America, re-.

heated by electrical action to separatethe same from the ore.

Briefly described, my invention consists of a suitable furnace surrounded by a waterjacket and having projecting through the walls into the interior of the furnace aseries of electrodes, which are arranged in pairs and at an angle to the wall of the furnace.

lVhen the ore is placed in the furnace, the contact of the same with the electrodes forms an arc, and the metals in the ore are separated therefrom, and being reduced to a molten state they fall to the bottom of the furnace and are removed by suitable means therefrom. Means is also provided for collecting the gases generated in the furnace during the decomposition of the ores, and, furthermore, with suitable connections for forcing air or steam through the ores to increase combustion and creating a downdraft within the furnace and at the same time expelling the gases into the storage-chamber.

In describing the invention in detail reference is had to the accompanying drawings, forming a part of this specification, and wherein like numerals of reference indicate corresponding parts throughout both views thereof, and in which- Figure 1 is a vertical sectional view of my improved furnace. Fig. 2isalike view showing modified form of furnace with collectingtank for the gases.

Referring now to the drawings, 1 indicates the walls of the furnace, which are preferably composed of any refractory material. This furnace-wall is surrounded by a water- ;jacket, in which 2 indicates the inner wall,

Serial No. 645,814. (No model.)

and 3 the outer wall. This jacket is preferably composed of a metallic material.

A hopper 4 is arranged in the upper part of thefurnace and is provided with a bellclosure 5, the latter being supported and operated in any of the well-known manners. The furnace is provided at its bottom with a blow-off pipe 6 and also has arranged in its side, near the bottom, the draw-off pipes 7 and 8 for removing the molten metal from the furnace. The furnace is further provided with a suitable water-supply 9, having a cutoh 10, for cleaning the interior of the furnace.

11 indicates agas-tank arranged at one side and connected to the furnace by means of the branch 12. This tank is provided with an elbow-shaped branch 16, the free end thereof 1 projecting into a water seal 16. This tank 11 has mounted on the top thereof anexhaustfan 13, connected to the tank 11 by means of a pipe 14, and has a pipe connecting the same to a storage-tank. (Not shown.)

Arranged around the furnace, near the top thereof, is a supply-pipe 17, connected by means of the pipes 18 to the interior of the furnace. This supply-pipe 17 is connected to a three-way cock or union 17, having pipes 19 and 20 communicating therewith for furnishing air or steam or air and steam separately to the supply-pipe 17, which is 0011- injected into the furnace to cause a downdraft as well as increasing combustion. The pipes 19 and 20 have arranged therein suitable cut-offs 21 and 22.

Extending through the water-jacket and wall of the furnace at an incline to the furnance-wall is a series of tubes 23, which are arranged in two spiral rows around the furnace in such amanner that the tubes of one row willbe opposite the tubes of the other row on the opposite side of the furnace. These tubes are adapted to receive and support the inwardly extending electrodes 24:, having suitable electrical connections 25 to a source of electrical supply. These electrodes extend for some distance into the furnace, the ends of the one row of electrodes on the one side of the furnace being opposite to the ends of the other row on the opposite side of the furnace, so that as the ore comes in contact with the inner end of the electrodes an arc is nected to the pipes 18, the air or steam being.

formed, and the current passing through the ore produces sufficient heat to reduce the metal to a molten state, which when in such condition falls to the bottom of the'furnace and is drawn through the pipes 7 and 8, while the gases resulting therefrom are carried off through the branch 12 into the tank 11,where they are exhausted therefrom by means of the exhaust-fan 13 and its connections into a suitable storage-receptacle. If desired, any well-known means maybe employed for cooling the gases within the tank 11 or otherwise.

In Fig. 2 of the drawings I have shown a cooling-tank for the gas, consisting of the closed tank 26, containing a suitable cooling medium. This tank is connected to the furnace by means of the branch 27, registering with the discharge-pipe 27 for the gas,which is arranged spirally within the tank. The upper end of this pipe 27 is connected to the exhaust-fan 28 by the pipe connections 29. 30 indicates a pipe which is connected at its one end to the exhaust-fan 28 and at its other end to a gas-storage chamber. (Not shown.)

It will of course be observed that the ore is fed into the furnace through the hopper 4 and that the hell-closure 5 normally closes the same, excepting during the charging operation. During the reducing or separation of the ores a downdraft is obtained and the combustion increased by means of the supply-pipe 17 and its various connections, as heretofore described.

It will be noted that various changes may be made in the details of construction without departing from the general spirit of my invention.

Having fully described my invention, What I claim as new, and desire to secure by Letters Patent, is-- 1. In an electrical downdraft-furnace, hav-' ing walls of suitable refractory material, a jacket of metal surrounding said walls and provided with a receptacle to receive cooling means, two sets of spirally-arranged elecsurrounding said receptacle, a hopper ranged in the upper part of said receptacle, a bell-shaped closure for said hopper, a double series of spirally-arranged electrodes proj ecting through the water-jacket and wall of the furnace and at an angle to the face thereof,

flues arranged in the lower part of the furnace whereby the by-products are removed, and means carried by the upper part of the furnace whereby water and vapor are supplied to aid combustion, substantially as herein shown and described.

3. In an electrical furnace, a receptacle provided with a suitable closure, fiues communicating with the lower part of said receptacle, two rows of spirally-arranged electrodes projecting through the receptacle and at an angle to the face thereof, a water-jacket sur-- rounding said receptacle, a tank arranged at one side of said furnace and communicating therewith by means of a pipe, and a fan secured to the top of said tank whereby the gaseous products generated in the furnace are exhausted,substantially as herein shown and described.

In testimony whereof I affix my signature in presence of two witnesses.

ROBERT H. LAIRD.

Witnesses:

W. H. TIMMERMANN, THOS. M. BOYD, Jr. 

